West Antarctica is warming almost twice as fast as previously believed, a new study shows, heightening fears of a catastrophic thaw that raise water levels from San Francisco to Shanghai.

Annual average temperatures at the Byrd research station there have risen 2.4C (4.3F) since the Fifties, it said, one of the fastest gains on the planet and three times the global average.

West Antarctica holds enough ice to raise world sea levels by at least 3.3m (11ft) if it ever all melted.

Melting: A new study raises the alarm over rising sea levels due to climate change in the Antarctic

Heating up: On this map, the colour intensity indicates areas around Antarctica that are likely experiencing comparable warming to Byrd Station, which is marked by the star

That process would take centuries, but even a much more modest thaw could threaten low-lying areas and coastal cities across the planet.

'Continued summer warming in West Antarctica could upset the surface mass balance of the ice sheet, so that the region could make an even bigger contribution to sea level rise than it already does,' said David Bromwich, professor of geography at Ohio State University and senior research scientist at the Byrd station.

'Even without generating significant mass loss directly, surface melting on the WAIS could contribute to sea level indirectly, by weakening the West Antarctic ice shelves that restrain the region's natural ice flow into the ocean.'

Low-lying nations from Bangladesh to
Tuvalu are especially vulnerable to sea level rise, as are coastal
cities from London to Buenos Aires.

Sea levels have risen by about 20cm
(8in) over the past century.

The
United Nations panel of climate experts projects that sea levels will
rise by between 18 and 59cm (7-24in) this century, and by more if a thaw
of Greenland and Antarctica accelerates.

Byrd Polar Research Center, pictured in 1960: Due to its location some 700 miles from the South Pole and near the center of the WAIS, Byrd Station is an important indicator of climate change throughout the region

Andrew Monaghan, study co-author and scientist at the National Center for Atmospheric Research, said that the new findings place West Antarctica among the fastest-warming regions on Earth.

The rise in temperatures in the remote region was comparable to that on the Antarctic Peninsula to the north, which snakes up towards South America, according to the U.S.-based experts writing in the journal Nature Geoscience.

Parts of the northern hemisphere have also warmed at similarly fast rates.

Several ice shelves - thick ice floating on the ocean and linked to land - have collapsed around the Antarctic Peninsula in recent years. Once ice shelves break up, glaciers pent up behind them can slide faster into the sea, raising water levels.

Patchy data: Since its establishment in 1957,
Byrd Station hasn't always been occupied and even after it was automated
it has been subject to frequent power cuts, so
scientists were forced to reconstruct readings

'We've already seen enhanced surface
melting contribute to the breakup of the Antarctic's Larsen B Ice Shelf,
where glaciers at the edge discharged massive sections of ice into the
ocean that contributed to sea level rise,' Dr Monaghan said.

'The stakes would be much higher if a similar event occurred to an ice shelf restraining one of the enormous WAIS glaciers.'

COULD WE REFREEZE THE ARTIC?

We could refreeze the Arctic, and it wouldn't even cost that much, a scientist claims.

Two recently published studies explore the possibility that a technological solution could be found to the problem of global warming melting the ice caps on the North Pole.

The scientist who is lead author on both claims that 'any significant nation' could find the resources to carry out the operation. The only significant question, he says, is whether we should.

The amount of ice in the Arctic Ocean shrank to an all time low in September (see graphic above), with the total area covered now half what it was in the Eighties.

David Keith, professor of applied physics at Harvard University, is lead author on papers published in Nature Climate Change and Environmental Research Letters which speculate as to how we could restore the polar ice.

He used climate models to suggest injecting reflective particles into the atmosphere could reduce the amount of sunlight reaching the Earth, engineering a regional effect that could bring ice back to the Arctic.

His paper claims that by reducing the penetration of sunlight by just 0.5 per cent is could be possible to restore the sea-ice around the North Pole back to pre-industrial era levels.

His second paper suggests the whole operation could be accomplished with just a few modified Gulfstream jets, costing somewhere in the region of $8billion a year.

However, while he believes action must be taken to tackle the amount of pollution spewed into the Earth's atmosphere, he doesn't yet advocate the kind of action his papers suggest.

Since the base of the ice sheet rests below sea level, it is vulnerable to direct contact with warm ocean water.

Its
melting currently contributes 0.3mm to sea level rise each year —
second to Greenland, whose contribution to sea level rise has been
estimated as high as 0.7mm per year.

Due to its location some 700 miles
from the South Pole and near the center of the WAIS, Byrd Station is an
important indicator of climate change throughout the region.

In the past, researchers haven't been able to make much use of the Byrd Station measurements. Data was often incomplete because nearly one third of the temperature observations were missing for the time period of the study.

Since its establishment in 1957, the station hasn't always been occupied. A year-round automated station was installed in 1980, but it has experienced frequent power cuts, especially during the long polar night, when its solar panels can't recharge.

Professor Bromwich and two of his graduate students, along with colleagues from NCAR and the University of Wisconsin-Madison, corrected the past Byrd temperature measurements and used corrected data from a computer atmospheric model and a numerical analysis method to fill in the missing observations.

Aside from offering a more complete picture of warming in West Antarctica, the study suggests that if this warming trend continues, melting will become more extensive in the region in the future, Professor Bromwich said.

While the researchers work to fully understand the cause of the summer warming at Byrd Station, the next step is clear, he added.

'West Antarctica is one of the most rapidly changing regions on Earth, but it is also one of the least known,' he said.

'Our study underscores the need for a reliable network of meteorological observations throughout West Antarctica, so that we can know what is happening—and why—with more certainty.'

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West Antarctic warming TWICE as fast as previously thought: Study raises the alarm over rise in sea levels